Piezoelectric Material, Multilayer Actuator and Method for Manufacturing a Piezoelectric Component

ABSTRACT

A piezoelectric material contains a material with the molecular formula P 1−c−d D c Z d , wherein: 0&lt;c≦0.15 and 0≦d≦0.5, wherein P represents the composition Pb(Zr 1−y Ti y )O 3  and wherein: 0.50≦1−y≦0.60, wherein Z represents an additional component of the perovskite type of structure, wherein D represents a material according to the general formula [(M 1 O) 1−p (M 2 O) p ] a [Nb 2 O 5 ] 1−a , wherein M 1  represents Ba 1−t Sr t  with 0≦t≦1 and M 2  represents strontium or calcium and wherein: ⅔&lt;a&lt;1 and 0&lt;p&lt;1, wherein the material D contains the cryolite type of structure.

This application is a continuation of co-pending InternationalApplication No. PCT/EP2008/052385, filed Feb. 27, 2008, which designatedthe United States and was not published in English, and which claimspriority to German Application No. 10 2007 010 239.0 filed Mar. 2, 2007,both of which applications are incorporated herein by reference.

TECHNICAL FIELD

The invention relates to a piezoelectric material that is suitable formanufacturing piezoelectric components with internal electrodes. Theinvention further pertains to a piezoelectric multilayer actuator andmethod for manufacturing a piezoelectric component.

BACKGROUND

A piezoelectric ceramic material is known from the publication DE 102004 002 204 A1 and U.S. equivalent publication 2007/0158608.

SUMMARY

In one aspect, the present invention specifies a piezoelectric materialthat is well suited for application in piezoelectric multilayeractuators.

A ceramic material that is based on PZT (lead zirconate titanate) isdescribed. In one example, a piezoelectric material comprises a materialwith the molecular formula P_(1−c−d)D_(c)Z_(d), where 0<c≦0.15 and0≦d≦0.5. In this formula, P represents the compositionPb(Zr_(1−y)Ti_(y))O₃, where 0.50≦1−y≦0.60, Z represents an additionalcomponent of the perovskite type of structure, and D represents amaterial according to the general formula[(M₁O)_(1−p)(M₂O)_(p)]_(a)[Nb₂O₅]_(1−a). M₁ represents Ba_(1−t)Sr_(t)with 0≦t≦1 and M₂ strontium, and wherein: ⅔<a<1 and 0<p<1. Preferably,the material D contains the cryolite type of structure.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The use of piezoelectric components as actuators places highrequirements for reliability as well as temporal and thermal stability,especially in automotive engineering. In addition, this use demands highdynamic actuator deviations in combination with a high blocking forcethat result when an electrical potential is applied to the actuator.Particularly suitable materials are piezoelectric ceramics based on leadzirconate titanate (Pb(Zr_(1−y)Ti_(y))O₃, PZT). In the case of PZTceramics, the desired piezoelectric material properties are achievedinitially by adjusting a defined quantity ratio between zirconium (Zr)and titanium (Ti) in the perovskite structure (ABO₃-type) of PZTcorresponding to the general formula Pb(Zr_(1−y)Ti_(y))O₃. Particularlyadvantageous piezoelectric properties are achieved with PZT materials ifthe Zr/Ti ratio lies in the area of the so-called morphotropic phaseboundary (MPB). Therefore, PZT materials according toPb(Zr_(1−y)Ti_(y))O₃, with y≈0.45-0.50, are preferably selected. Inaddition, the material properties of PZT can be adjusted veryextensively and specifically for the respective application by theaddition of certain materials that can dissolve in the perovskitestructure of PZT, and are referred to as doping materials or dopants.The modification of a PZT material can be achieved, for example, bysubstitution of Pb at A-sites (Pb sites) and/or by substitution of theZr/Ti system B-sites (Zr/Ti sites) with suitable elements or suitablecombinations of elements. Not lowering the comparatively high Curietemperature T_(C) of≈360° C. too sharply by such material modificationsis particularly advantageous for the thermal stability of piezoelectricPZT materials. This is successfully accomplished particularly by keepingthe concentration of the additives or dopants as small as possible.

The piezoelectric material described here contains, in addition to thePZT base material, an additive present in the form of such a dopant.With the aid of an additive to the PZT base material, lattice sites ofthe PZT base lattice can be occupied by materials other than thosepredefined by PZT, whereby the electrical and mechanical properties ofthe material can be favorably influenced. The dopant is preferablypresent in the piezoelectric material in a proportion of up to 2.5 mol%. It is particularly preferred if a mixed crystal, wherein the leadzirconate titanate and the dopant form a solid solution, forms from thePZT base material and the dopant. In particular, the installation ofcations at B-sites of the PZT host lattice is possible by doping PZT,whereby the electrical properties of the material can be particularlyextensively improved.

As a dopant, a ceramic material considered particularly preferable isone that corresponds to the general formula[M₁O)_(1−p)(M₂O)_(p)]_(a)[Nb₂O₅]_(1−a), wherein M₁ representsBa_(1−t)Sr_(t) with 0≦t≦1 and M₂ represents strontium or calcium andwherein: ⅔<a<1 and 0<p<1.

The installation of M₂ cations at formal B-sites of the perovskite hostlattice is possible with the aid of the specified mixture of PZT and thedopant of the specified formula. This is true particularly because thePZT base material and the dopant form a mixed crystal. The compositionPb(Zr_(1−y)Ti_(y))O₃ is considered particularly favorable wherein as thePZT base material: 0.50≦1−y≦0.60, and wherein the host latticecorresponds to the lattice ABO₃ of the perovskite type. By selecting theparameter 1−y to be between 0.5 and 0.6, the zirconium/titanium ratio isadjusted to the area of the so-called morphotropic phase boundary, whichbrings about particularly good properties of the ceramic material.

According to another embodiment of the piezoelectric material, an extracomponent of the perovskite type of structure can additionally becontained up to a proportion of 50 mol %.

The dopant can contain the cryolite type of structure, whereby aparticularly good solubility of the dopant or parts of the dopant in thePZT host lattice results.

The dopant can be present in the host lattice as a compound with acryolite structure in solid solution.

With respect to the dopant, three different stoichiometric compositionsor parameter ranges can be distinguished:

in parameter range 1: 6/7<a<1,

in parameter range 2: ⅔<a<⅘, and

in parameter range 3: ⅘≦a≦ 6/7 and ¼≦p≦⅓.

In parameter range 3, a formulation of a compound with cryolitestructure results for the dopant for the case in which the parameter pcorrelated with the parameter a varies, specifically, according to therelationship a= 22/35+24p/35, which produces a connection between a andp. The general formula for the underlying cryolite system is:

(M₁)₄[(M₂)_(2−2x/3)Nb_(2+2x/3)]O₁₁+_(x)V_(O;1−x) with 0≦x≦1,

wherein it holds for the relationship between a and the parameter xthat:

a= 6/7−2x/35.

The cryolite compound has a phase range corresponding to the range ofvariation 0≦x≦1 and the presence of oxygen vacancies (V_(O)). Moreover,the cryolite structure corresponds very closely to the closely relatedPZT perovskite host lattice. Both ceramic materials can form amixed-crystal system in which the components of the dopant are insertedonto the lattice sites of the PZT lattice. They thus form a solidsolution, i.e., in the perovskite phase, vacancies on the oxygen sitesoccur in the range x<1, and M₂ is installed onto the B-sites of theuniform perovskite phase.

In the case where M₁=M₂=Sr, strontium cations are installed on theB-sites of the perovskite phase.

In parameter range 1, the existing excess of {M₁O and/or M₂O}, in theboundaries of 1/7 (for a=1) and 0 (for a= 6/7), enters into a chemicalreaction with the PZT host lattice.

For the excess of alkaline-earth oxide, the ratio of M₁ to M₂ can bevaried arbitrarily according to 0<p<1, and the following reactions canoccur:

M₁O+Pb(Zr_(1−y)Ti_(y))O₃⇄M₁(Zr_(1−y)Ti_(y))O₃+PbO  Equation <1a>

M₂O+Pb(Zr_(1−y)Ti_(y))O₃⇄M₂(Zr_(1−y)Ti_(y))O₃+PbO  Equation <1b>

The PbO can be forced out of the PZT host lattice with the aid of thesereactions, and an equivalent amount M(Zr_(1−y)Ti_(y))O₃ is formed, whereM represents M₁ or M₂. These zirconium titanates that are formed canlikewise dissolve in the PZT host lattice, forming a mixed crystal. Inaddition, lead oxide is produced which slightly further increases thecontent of any sintering aid that may already be present in the system.Said reaction can run until a= 6/7 is reached. In this case, an amountof M₁O and/or M₂O equivalent to the Nb₂O₅ content is present in thematerial, and with p=⅓, the solid solution of the cryolite with thelimit composition (M₁)₄[(M₂)₂Nb₂]O₁₁V_(O;1) in the PZT host latticeresults. The solid solution contains M₂ cations at B-sites of theperovskite mixed crystal and oxygen vacancies.

The limit composition corresponds to the parameter x=0 corresponding toone side of the phase range of the cryolite system. In this case, theoxygen vacancy concentration is relatively high.

For the case where M₁=M₂, there is an excess of strontium oxide in theboundaries 0<{SrO}< 1/7. The displacement of PbO from the PZT hostlattice runs according to the following reaction equation:

SrO+Pb(Zr_(1−y)Ti_(y))O₃⇄Sr(Zr_(1−y)Ti_(y))O₃+PbO  Equation <2>

With the aid of this reaction, an equivalent amount ofSr(Zr_(1−y)Ti_(y))O₃ is formed, which dissolves in the PZT host lattice,forming a mixed crystal. An amount of SrO equivalent to the Nb₂O₅content, corresponding to an excess of strontium oxide of 0, results inthe formation of a solid solution of the cryolite compound with thelimit composition Sr₄(Sr₂Nb₂)O₁₁V_(O;1) in the PZT host lattice,according to the other side of the phase range in the cryolite system.The solid solution contains Sr cations at B-sites of the perovskitemixed crystal and oxygen vacancies.

In parameter range 2, there is an excess of niobium oxide {Nb₂O₅} in therange ⅕>{Nb₂O₅}>0, which leads, as a consequence of the binding ofsintering aid PbO possibly present in the system or added to it,according to:

Nb₂O₅+PbO ⇄2Pb_(0.5)V_(Pb;0.5)NbO₃  Equation <3>

to the formation of an equivalent amount of lead niobate. The leadniobate can likewise dissolve in the PZT lattice, forming a mixedcrystal, wherein the formation of lead vacancies V_(Pb) occurs at the Pbsites of the PZT host lattice. If the parameter p=¼ is satisfied, then acontent of Nb₂O₅ equivalent to the M₁O or M₂O content, corresponding toa=⅘, results in the formation of a solid solution of the cryolitecompound with the limit composition (M₁)₄[(M₂)_(4/3)Nb_(8/3)]O₁₂ in thePZT host lattice, according to the other side of the phase range of thecryolite system, wherein in this case, M₂ cations continue to be presenton B-sites of the perovskite mixed crystal, but the oxygen vacancies areeliminated.

For the case of M₁=M₂=Sr, the parameter p is unnecessary and in the caseof a content of Nb₂O₅ equivalent to the strontium oxide content, thereresults the formation of a solid solution of the cryolite compound withthe limit composition Sr₄(Sr_(4/3)Nb_(8/3))O₁₂ according to the otherside of the phase range of the cryolite system, wherein no oxygenvacancies are present, but the B-sites of the perovskite mixed crystalstill contain Sr cations.

It is true in general of all the piezoelectric materials described herethat they can additionally contain up to 5 mol % of PbO. This lead oxidecan serve, for example, as an auxiliary agent in the sintering of theceramic material.

According to a particularly preferred embodiment of the material, thedopant contains a cryolite compound of the formula(M₁)₄[(M₂)₂Nb₂]O₁₁V_(O;1), which forms a solid solution with the PZThost lattice.

In general, the piezoelectric material can be described with the summaryformula P_(1−c−d)D_(c)Z_(d), where,

0<c≦0.15 and 0≦d≦0.5.

Here the subranges 0<c≦0.025 and 0.0255<c<0.0443 are possible for c.Here P represents the PZT base material, D the dopant with the generalcomposition [(M₁O)_(1−p)(M₂O)_(p)]_(a)[Nb₂O₅]_(1−a), and Z an additionalcomponent of the perovskite type of structure.

The cryolite compound of the formula (M₁)₄[(M₂)₂Nb₂]O₁₁V_(O;1) can be aconstituent of component D, wherein the excess of MO of component D isreacted with component P to M(Zr_(1−y)Ti_(y))O₃ and PbO, wherein Mrepresents M₁ or M₂.

According to another embodiment of the material, the dopant can containa cryolite compound of the formula (M₁)₄[(M₂)_(4/3)Nb_(8/3)]O₁₂, whichforms a solid solution with the PZT host lattice. The cryolite compoundcan be a constituent of component D, with an excess of Nb₂O₅ ofcomponent D being reacted with PbO additionally present in the ceramicmaterial into lead niobate.

According to one embodiment of the material, M(Zr_(1−y)Ti_(y))O₃ can becontained in the material as the product of a reaction of theabove-described cryolite system with component P, where M represents M₁or M₂.

Due to the dopants that are present only in small amounts, aninteraction and reaction with the PZT host lattice, preset in a largeexcess, can come about for the cryolite compound. In this manner, aconsiderable modification of the oxygen vacancy concentration in theentire material system can be achieved.

Due to the greater basicity of the alkaline-earth component in thedopant, the mixed crystal formation of the dopant with the PZT hostlattice includes the possibility of displacement of PbO from the PZT.This is true particularly in the range of formulating a solid solutionof a compound from the above-described cryolite system in the PZT hostlattice. The reactions coming into consideration read as follows:

(M₁)₄[(M₂)₂Nb₂]O₁₁V_(O)+ 8/7Pb(Zr_(1−y)Ti_(y))O₃⇄6/7(M₁)₄[(M₂)_(5/3)Nb_(7/3))]O_(11.5)V_(O;0.5)+ 4/7M₁(Zr_(1−y)Ti_(y))O₃+4/7M₂(Zr_(1−y)Ti_(y))O₃+ 8/7PbO  Equation <4>

6/7(M₁)₄[(M₂)_(5/3)Nb_(7/3))]O_(11.5)V_(O;0.5)+6/7Pb(Zr_(1−y)Ti_(y))O₃⇄¾(M₁)₄[(M₂)_(4/3)Nb_(8/3)]O₁₂+3/7(M₁)Sr(Zr_(1−y)Ti_(y))O₃+ 3/7M₂(Zr_(1−y)Ti_(y))O₃+ 6/7PbO  Equation<5>

¾(M₁)₄[(M₂)_(4/3)Nb_(8/3)]O₁₂+4Pb(Zr_(1−y)Ti_(y))O₃⇄3M₁(Zr_(1−y)Ti_(y))O₃+2Pb_(0.5)V_(Pb;0.5)NbO₃+3PbO+1M₂(Zr_(1−y)Ti_(y))O₃  Equation<6>

If it ran completely to the end, equation <6> would mean a completetransition of the M₂ cations from the B-sites of the host lattice to theA-sites of the host lattice.

The formation of PbNb₂O₆, which is equivalent to 2 formula units ofPb_(0.5)V_(Pb;0.5)NbO₃, is connected with the last reaction equation. Asa consequence of a mixed crystal formation with the PZT host lattice,there is a formation of lead vacancies on the A-sites of the doped PZTceramic.

Corresponding to the specified reaction equations, a piezoelectricmaterial is specified, wherein (M₁)₄[(M₂)_(4/3)Nb_(8/3)]O₁₂ is convertedwith the PZT host lattice at least in part into lead niobate.

In addition, a piezoelectric material is specified, wherein(M₁)₄[(M₂)_(5/3)Nb_(7/3)]O_(11.5)V_(O;0.5) is converted with the PZThost lattice at least in part into (M₁)₄[(M₂)_(4/3)Nb_(8/3)]O₁₂.

In addition, a piezoelectric material is specified, wherein(M₁)₄[(M₂)₂Nb₂]O₁₁V_(O) is converted with the PZT host lattice at leastin part into (M₁)₄[(M₂)_(5/3)Nb_(7/3)]O_(11.5)V_(O;0.5).

The specified reactions allow the adjustment of a very variableconcentration of the oxygen vacancies. This elevation or reduction ofthe oxygen vacancy concentration can take place temperature-dependently,which offers a good possibility for the advantageous use of the oxygenvacancy variation in the sintering process of the ceramic material. Thiswill be explained below.

An exothermic reaction course due to the stronger basicity of thealkaline-earth oxide can be based on the displacement of PbO from thePZT host lattice that takes place according to the above equations. Thismeans that the equilibria shift at high temperatures in the direction ofan elevated concentration of oxygen vacancies, whereby the sinteringcompression and grain growth of the ceramic are promoted. Duringcooling, the equilibria shift to the side of a reduction of theconcentration of oxygen vacancies, which can lead to the completeelimination of such defects, which is advantageous for the functionalstability of the PZT ceramic.

Based on the specified reaction equations, the distribution pattern ofthe defects installed in the PZT host lattice by the dopant can becontrolled in the thermal treatment. Thereby the composition of thesolid solution of PZT base material and dopant changes.

Accordingly, a piezoelectric material that contains a lead zirconatetitanate ceramic, wherein the ceramic contains oxygen vacancies atlattice sites of the PZT lattice and wherein the concentration of theoxygen vacancies is temperature-dependent, is also specified.

According to one embodiment, a material in which the concentration ofoxygen vacancies increases with rising temperature is additionallyspecified.

In a particularly preferred embodiment, the oxygen vacancy concentrationruns largely temperature-dependently in a temperature range between 0and 1200° C. This material has the advantage that the temperaturedependency of the oxygen vacancy concentration can be made useful in asintering process for manufacturing the ceramic material. The sinteringtemperature for the materials specified here lies between 900 and 1200°C.

According to a special embodiment of the piezoelectric material, thecation constituent is selected such that:

M₁=M₂=Sr.

From this, compounds from the above-described cryolite system accordingto the formula Sr₄(Sr_(2−2x/3)Nb_(2+2x/3))O_(11+x)V_(O;1−x), result,wherein 0≦x≦1. A part of the strontium cations here occupy the formalB-sites of component P. As a product of a reaction of component P withcomponent D, the specified material can contain Sr(Zr_(1−y)Ti_(y))O₃.This material can exist in the form of a solid solution with the PZThost lattice.

The reactions between the dopant and the PZT host lattice can run asfollows in this case:

Sr₄(Sr₂Nb₂)O₁₁V_(O)+ 8/7Pb(Zr_(1−y)Ti_(y))O₃⇄6/7Sr₄(Sr_(5/3)Nb_(7/3))O_(11.5)V_(O;0.5)+ 8/7Sr(Zr_(1−y)Ti_(y))O₃+8/7PbO  Equation <7>

6/7Sr₄(Sr_(5/3)Nb_(7/3))O_(11.5)V_(O;0.5)+6/7Pb(Zr_(1−y)Ti_(y))O₃⇄¾Sr₄(Sr_(4/3)Nb_(8/3))O₁₂+6/7Sr(Zr_(1−y)Ti_(y))O₃+ 6/7PbO  Equation <8>

¾Sr₄(Sr_(4/3)Nb_(8/3))O₁₂+4Pb(Zr_(1−y)Ti_(y))O₃⇄4Sr(Zr_(1−y)Ti_(y))O₃+2Pb_(0.5)V_(Pb;0.5)NbO₃+3PbO  Equation<9>

According to a special embodiment of the material, the composition readsP_(1−c−d)D_(c)Z_(d)[PbO]_(m), wherein D represents a cryolite compoundwith the formula [(SrO)_(a)(Nb₂O₅)_(1−a)] with a= 29/35, which can beexpressed by the equivalent cryolite notation,

Sr₄(Sr_(5/3)Nb_(7/3))O_(11.5)V_(0;0.5), wherein:

0<c≦0.15 and 0≦m≦0.05, d=0.

Here the subranges 0<c≦0.025 and 0.0255<c<0.0443 are possible for c.

In a particularly special embodiment, a material is specified which has,for 1−y=0.53 with c=0.005 and m=0.01, a composition according to theformula:

[Pb(Zr_(0.53)Ti_(0.47))O₃]_(0.973)[Sr₄(Sr_(4/3)Nb_(8/3))O₁₂]_(0.00213)

[Sr(Zr_(0.53)Ti_(0.47))O₃]_(0.017)[PbV_(Pb)(Nb₂O₆)]_(0.003)(PbO)_(0.029).

In the ceramic material with the specially specified formula, roughly10% of the strontium cations occupy the formal B-sites of the PZT hostlattice.

According to another embodiment, a piezoelectric material with thecomposition P_(1−c−d)D_(c)Z_(d)[PbO]_(m) is specified, wherein Drepresents a cryolite compound according to the formula[(BaO)_(1−p)(CaO)_(p)]_(a)(Nb₂O₅)_(1−a)] with a= 29/35 and p= 7/24,which can be expressed by the equivalent cryolite notationBa₄(Ca_(5/3)Nb_(7/3))O_(11.5)V_(0;0.5), wherein:

0<c≦0.15 and 0≦m≦0.05, d=0.

Here the subranges 0<c≦0.025 and 0.0255<c<0.0443 are possible for c.

According to a particularly special formulation, a material is specifiedthat, for 1−y=0.53 with c=0.005 and m=0.01, has a composition accordingto the formula:

[Pb(Zr_(0.53)Ti_(0.47))O₃]_(0.973)[Ba₄(Ca_(4/3)Nb_(8/3))O₁₂]_(0.00213)

[Ba(Zr_(0.53)Ti_(0.47))O₃]_(0.0115)[Ca(Zr_(0.53)Ti_(0.47))O₃]_(0.0055)

[PbV_(Pb)(Nb₂O₆)]_(0.003)(PbO)_(0.029).

In this case roughly 34% of the calcium cations occupy formal B-sites ofthe PZT host lattice.

The case M₁=M₂=Sr will once again be described in detail below.

According to one embodiment, a strontium niobate mixture according tothe formula (SrO)_(a)(Nb₂O₅)_(1−a) in the range 1>a>⅔ is used as adopant for the PZT ceramic. A contraction of NbO_(6/2) octahedra isconnected with the installation of Nb⁵⁺ cations on B-sites of theperovskite structure of the PZT host lattice, whereby a widening ofadjacent oxygen octahedra results and, connected thereto, theinstallation of relatively large Sr cations on B-sites of the PZT hostlattice with the coordination number=6 is made possible.

It must be noted here that (SrO)_(a)(Nb₂O₅)_(1−a) can interact with thelead zirconium titanate host lattice, forming strontium zirconiumtitanate (SZT), and can form Pb(Nb₂O₆) within the range 1>a>⅔(thiscorresponds to Pb_(0.5)V_(Pb;0.5)NbO₃), which dissolves in the PZT hostlattice with lead vacancies (V_(Pb)) at the formal A-sites as well asSZT, forming mixed crystals. This takes place according to the followingreaction equation:

(SrO)_(a)(Nb₂O₅)_(1−a) +aPb(Zr_(1−y)Ti_(y))O₃⇄(1−a)PbNb₂O₆+aSr(Zr_(1−y)Ti_(y))O₃+(2a−1)PbO  Equation <10>

In the range 1>a> 6/7, (SrO)_(a)(Nb₂O₅)_(1−a) reacts with PZT until a=6/7 is reached, with liberation of PbO, which is added to the 0.1-5 mol% PbO generally already present in the mixture, and acts as a sinteringaid.

SrO+Pb(Zr_(1−y)Ti_(y))O₃⇄Sr(Zr_(1−y)Ti_(y))O₃+PbO  Equation <2>

For the case where a= 6/7, there is the option of a mixed crystalformation in the PZT host lattice with the cryolite compoundSr₄(Sr₂Nb₂)O₁₁V_(O;1), wherein Sr ions are contained on B-sites as wellas on oxygen vacancies. The cooperation of this cryolite compound in thePZT/dopant mixed-crystal system takes effect in the entire range withthe limits 1>a > 6/7, i.e., the possibility of occupation of B-sites bySr cations in the PZT host lattice always accompanies the installationof Nb cations.

Due to a mixed crystal formation with the PZT perovskite host lattice,the cryolite system with the formulaSr₄(Sr_(2−2x/3)Nb_(2+2x/3))O_(11+x)V_(O;1−x) with a phase range withinthe range 0≦x≦1 is particularly suited to the doping of PZT ceramics.For mixtures according to the general formula (SrO)_(a)(Nb₂O₅)_(1−a),the phase range of the cryolite system is determined by the limits6/7≧a≧⅘. A variable concentration of oxygen vacancies V_(O) accompaniesthis variable composition inside the phase range. With the limitcomposition x=0 (in this case a= 6/7) for example, the solid solution ofSr₄(Sr₂Nb₂)O₁₁V_(O;1) in the PZT host lattice results, with acomparatively high oxygen vacancy concentration of [V_(O)]=1. For x=½(inthis case a= 34/41), a mean oxygen vacancy concentration of [V_(O)]=0.5follows, with the corresponding formulaSr₄(Sr_(5/3)Nb_(7/3))O₁₁V_(O;0.5). In the case of the limit compositionwith x=1 (in this case a=⅘), which corresponds to the formulaSr₄(Sr_(4/3)Nb_(8/3))O₁₂, no more oxygen vacancies are left, becausethere is now a valence compensation on the B-sites that includes anoccupation of B-sites by Sr cations.

For the dopant with the composition (SrO)_(a)(Nb₂O₅)_(1−a) in the rangeof ⅘≧a≧⅔, the formation of the compound Pb_(0.5)V_(Pb;0.5)NbO₃ with leadvacancies (V_(Pb)) on the A-sites of the PZT-perovskite mixed crystalcomes about because the content of Nb₂O₅ exceeds the limit compositionof the cryolite system, with a part of the lead oxide (PbO) added as asintering aid being bound. The displacement of PbO by SrO in the dopedPZT mixed-crystal system as described in equations <7>, <8> and <9> isproduced by the basicity difference of PbO and SrO. The exothermiccharacter of the acid-base reaction has the consequence that, withrising temperature (e.g., during sintering), the above-describedequilibrium reactions shift towards the side of the reactants, i.e.,towards the left side of the equilibrium reactions. One advantage ofthis largely temperature-dependent equilibrium shift is that theformation of an (at least temporarily) elevated oxygen vacancyconcentration during sintering is promoted as a consequence of thedoping with (SrO)_(a)(Nb₂O₅)_(1−a) in the range 1>a>⅔, which has a verypositive effect on sintering compression and the formation of anoptimized structural texture of the ceramic. During the cool-down aftersintering, the equilibrium reactions are shifted towards the side of theproducts, i.e., the right-hand side of the equilibrium reaction, withthe excretion of an amount of PbO equivalent to the degree of doping.Particularly advantageous here is the simultaneous considerablereduction or even elimination of elevated oxygen vacancy concentration,which is unfavorable for the long-term stability of the piezoelectricmaterial, particularly during use in an electric field. The interactionof the dopant in the solid solution with the PZT host lattice caninclude the complete migration of the Sr cations from the formal B-sitesto the formal A-sites, i.e., partial substitution of Pb cations withcoordination number=12.

The proportion of Sr cations after heat processing on both the formalA-sites (coordination number=12) and on the formal B-sites (coordinationnumber=6) in the piezoelectric materials described here was analyzed andquantified by means of high-resolution solid-state analyticalmeasurement methods. Remarkably high concentrations of Sr cations on theformal B-sites, e.g., a proportion of roughly 10% of the entire contentof Sr, were unambiguously detected. One conclusion of these studies isthat during cooling after sintering, the specified reaction according toequation <9> does not run completely to the side of the reactionproducts.

With a nearly complete elimination of the oxygen vacancies in PZTceramic doped with (SrO)_(a)(Nb₂O₅)_(1−a) in the range 1>a>⅔, aconsiderable proportion of the total strontium content remains on theB-sites of the perovskite mixed crystal of the piezoelectric material,whereby the outstanding material properties, particularly for use inpiezoelectric multilayer actuators, originate.

In addition, a piezoelectric material is specified which furthercontains the additive component Z in the PZT mixed-crystal system. Themodification and adaptation of the piezoelectric properties topredetermined values is thereby made possible. The additive component Zcan comprise the compounds listed below:

[Pb(Fe^(III) _(2/3)W^(VI) _(1/3))O₃].

[Pb(M^(II) _(1/3)M^(V) _(2/3))O₃], wherein M^(II) represents Mg, Zn, Co,Ni, Mn or Cu, and M^(V) for Nb, Ta or Sb,

[PB(M^(III) _(1/2)M^(V) _(1/2))O₃], wherein M^(III) represents Fe, Mn,Cr or Ga and M^(V) represents Nb, Ta or Sb,

[Pb(M^(III) _(2/3)M^(VI) _(1/3))O₃], wherein M^(III) represents Mn, Cr,Ga and M^(VI) represents W,

[Pb(Li^(I) _(1/4)M^(V) _(3/4))O₃], wherein M^(V) represents Nb, Ta orSb.

The piezoelectric material can additionally be free of [Pb(Fe^(III)_(2/3)W^(VI) _(1/3))O₃].

Furthermore, a piezoelectric multilayer actuator that comprises at leastone dielectric layer and at least two internal electrodes, wherein atleast one dielectric layer contains a piezoelectric material asdescribed here, is specified.

In addition, a method for manufacturing a piezoelectric component isdescribed, wherein the component contains the material described here,wherein the concentration of the oxygen vacancies is increased duringthe sintering and again lowered during the cooling of the ceramicmaterial.

The material will be explained in detail with the following examples.

Example 1

The doping of a PZT ceramic according to Pb(Zr_(0.53)Ti_(0.47))O₃ with,for example, 3.425 mol % (SrO)_(34/41)(Nb₂O₅)_(7/41) (this correspondsto 0.5 mol % [Sr₄(Sr_(5/3)Nb_(7/3))O_(11.5)V_(O;0.5)]) and addition of 1mol % PbO corresponding to the formula

[Pb(Zr_(0.53)Ti_(0.47))O₃]_(0.995)[Sr₄(Sr_(5/3)Nb_(7/3))O_(11.5)V_(O;0.5)]_(0.005)

[PbO]_(0.01)

leads during the thermal processing to a piezoelectric ceramic accordingto the formula

[Pb(Zr_(0.53)Ti_(0.47))O₃]_(0.973)[Sr₄(Sr_(4/3)Nb_(8/3))O₁₂]_(0.00213)

[Sr(Zr_(0.53)Ti_(0.47))O₃]_(0.017)[PbV_(Pb)(Nb₂O₆)]_(0.003)(PbO)_(0.029)

wherein the components in square brackets are soluble in one another,forming a perovskite mixed-crystal phase, and oxygen vacancies arepresent only in negligibly small concentrations. As a consequence of thedisplacement of PbO by SrO in conjunction with a release of Nb₂O₅, aformation of lead vacancies (V_(Pb)) on the formal A-sites (Pb-sites)occurs, and ca. 10% of the overall strontium content remains on theformal B-sites (Zr/Ti sites) in the vicinity of Nb cations withcoordination number 6.

Example 2

With respect to the dopant according to the formula(SrO)_(a)(Nb₂O₅)_(1−a) in the range 1>a ⅔, related systems that have asimilar structural constitution can be used alternatively oradditionally. For example, compounds according to the formula[(BaO)_(1−p)(CaO)_(p)]_(a)[Nb₂O₅]_(1−a) in the range 1>a>⅔ with 1<p<0can be used. In this case, in the range 6/7≧a≧⅘ with appropriatelyassociated parameter p in the range ⅓≧p≧¼, a mixed-crystal phase isformed between the cryolite system according to the formulaBa₄(Ca_(2−2x/3)Nb_(2+2x/3))O_(11+x)V_(O;1−x) with 0≦x≦1 as a dopant andPZT as the host lattice. The dopant in the mixed crystal is subject totemperature-dependent equilibrium reactions similar to those describedin equations <4> through <6>.

In the range 1>a> 6/7 with 1≧p≧0, compounds according to the formula[(BaO)_(1−p)(CaO)_(p)]_(a)[Nb₂O₅]_(1−a) react with PZT analogously tothe reaction equations <1a> and <1b> until, when a= 6/7 is reached withp=⅓, a PZT mixed-crystal phase is formed, with Ba₄(Ca₂Nb₂)O₁₁V_(O), acompound that appears in the cryolite type of structure with Ca cationson B-sites and contains oxygen vacancies VO. The cooperation of thiscryolite component in the PZT/dopant mixed-crystal system takes effectin the entire range inside the limits 1>a> 6/7, i.e., the installationof Nb cations on formal B-sites is always accompanied by the possibilityof the occupation by Ca cations on B-sites. Temperature-dependentreactions analogous to equations <4> through <6> must also be taken intoaccount.

For example, the doping of a PZT ceramic according to the formulaPb(Zr_(0.52)Ti_(0.48))O₃ with 3.425 mol %[(BaO)_(12/17)(CaO)_(5/17)]_(34/41)[Nb₂O₅]_(7/41) (corresponding to 0.5mol % [Ba₄(Ca_(5/3)Nb_(7/3))O_(11.5)V_(0.5)]) and addition of 1 mol %PbO corresponding to the formula

[Pb(Z_(0.52)Ti_(0.48))O₃]_(0.995)[Ba₄(Ca_(5/3)Nb_(7/3))O_(11.5)V_(0.5)]_(0.005)

[PbO]_(0.01)

yields, during thermal processing, a piezoelectric ceramic according tothe formula

[Pb(Zr_(0.52)Ti_(0.48))O₃]_(0.973)[Ba₄(Ca_(4/3)Nb_(8/3))O₁₂]_(0.00213)

[Ba(Zr_(0.52)Ti_(0.48))O₃]_(0.0115)[Ca(Zr_(0.52)Ti_(0.48))O₃]_(0.0055)

[PbV_(Pb)(Nb₂O₆)]_(0.003)(PbO)_(0.029)

wherein ca. 34% of the entire calcium content is installed on the formalB-sites of the perovskite mixed crystal.

In place of [(BaO)_(1−p)(CaO)_(p)]_(a)[Nb₂O₅]_(1−a) in the range 1>a>⅔,a material system according to the formula[(BaO)_(1−p)(SrO)_(p)]_(a)[Nb₂O₅] or a material system according to theformula [(SrO)_(1−p)(CaO)_(p)]_(a)[Nb₂O₅] can analogously be used as adopant, wherein the compounds formed in the range 6/7≧a≧⅘ withappropriately assigned parameter p in the range ⅓≧p≧¼ from the cryolitesystems

Ba₄(Ca_(2−x)/3Nb_(2+2x/3))O_(11+x)V_(O;1−x) orSr₄(Ca_(2−2x/3)Nb_(2+2x/3))O_(11+x)V_(O;1−x) with 0≦x≦1

dissolve in the PZT host lattice, forming a mixed crystal, and can enterinto a reaction with PZT in temperature-dependent equilibrium reactionsanalogous to equations <4> through <6>.

To produce the piezoelectric material described here, a mixture of Pb₃O₄or PbCO₃ with TiO₂ and ZrO₂ or optionally a (Zr_(1−y)Ti_(y))O₂precursor, as well as SrCO₃ and Nb₂O₅, and other additives such asPb(Fe^(III) _(2/3)W^(VI) _(1/3))O₃, if appropriate, are provided.Exemplary compositions are presented in Tables 1 and 2. Alternatively,SrCO₃ can also be replaced by a corresponding content of BaCO₃ or CaCO₃,or BaCO₃ is used instead of SrCO₃ as raw material in a proportionalcombination with SrCO₃ or CaCO₃. Alternatively, a mixture can also beused in which the alkaline-earth carbonates are replaced byalkaline-earth titanates such as SrTiO₃, BaTiO₃ or CaTiO₃ or by addingto the mixture, according to the desired composition, the respectiveproportion of prefabricated compound from the above-described cryolitecompounds such as those according to the formulas

Sr₄(Sr_(2−2x/3)Nb_(2+2x/3))O_(11+x)V_(O;1−x),

Ba₄(Sr_(2−2x/3)Nb_(2+2x/3))O_(11+x)V_(O;1−x),

Ba₄(Ca_(2−2x/3)Nb_(2+2x/3))O_(11+x)V_(O;1−x) or

Sr₄(Ca_(2−2x/3)Nb_(2+2x/3))O_(11+x)V_(O;1−x) with 0≦x≦1.

Exemplary compositions of materials with partial doping of Sr or Cacations on formal B-sites in the resulting PZT mixed-crystal phase withperovskite structure are listed in Tables 1 and 2.

Insofar as two numerical values are listed for the parameter d, theseare to be viewed in combination with the other parameter values in thesame row as separate embodiments.

TABLE 1 [Pb(Zr_(1−y)Ti_(y))O₃]_(1−c)[(Sro)_(a)(Nb₂O₅)_(1−a)]_(c)•0.01PbO 1 − y = 0.53 a = 34/41 c = 0.0255 1 − y = 0.53 a = 34/41 c = 0.03421 − y = 0.53 a = 34/41 c = 0.0443 1 − y = 0.535 a = 34/41 c = 0.0255 1 −y = 0.535 a = 34/41 c = 0.0342 1 − y = 0.535 a = 34/41 c = 0.0443[Pb(Zr_(1−y)Ti_(y))O₃]_(1−c−d)[Pb(Fe^(III) _(2/3)W^(VI) _(1/3))O₃]_(d)[(Sro)_(a)(Nb₂O₅)_(1−a)]_(c)•0.01 PbO 1 − y = 0.53 a = 34/41 c = 0.0255d = 0.003 or 0.008 1 − y = 0.53 a = 34/41 c = 0.0342 d = 0.003 or 0.0081 − y = 0.53 a = 34/41 c = 0.0443 d = 0.003 or 0.008 1 − y = 0.535 a =34/41 c = 0.0255 d = 0.003 or 0.008 1 − y = 0.535 a = 34/41 c = 0.0342 d= 0.003 or 0.008 1 − y = 0.535 a = 34/41 c = 0.0443 d = 0.003 or 0.008

TABLE 2[Pb(Zr_(1−y)Ti_(y))O₃]_(1−c){[(BaO)_(1−p)(CaO)_(p)]_(a)[Nb₂O₅]_(1−a)}c•0.01PbO 1 − y = 0.53 a = 34/41 c = 0.0255 p = 5/17 1 − y = 0.53 a = 34/41 c= 0.0342 p = 5/17 1 − y = 0.53 a = 34/41 c = 0.0443 p = 5/17 1 − y =0.535 a = 34/41 c = 0.0255 p = 5/17 1 − y = 0.535 a = 34/41 c = 0.0342 p= 5/17 1 − y = 0.535 a = 34/41 c = 0.0443 p = 5/17[Pb(Zr_(1−y)Ti_(y))O₃]_(1−c−d)[Pb(Fe^(III) _(2/3)W^(VI) _(1/2))O₃]_(d){[(BaO)_(1−p)(CaO)_(p)]_(a)[Nb₂O₅]_(1−a)}_(c)•0.01 PbO 1 − y = 0.53 a =34/41 c = 0.0255 p = 5/17 d = 0.003 or 0.008 1 − y = 0.53 a = 34/41 c =0.0342 p = 5/17 d = 0.003 or 0.008 1 − y = 0.53 a = 34/41 c = 0.0443 p =5/17 d = 0.003 or 0.008 1 − y = 0.535 a = 34/41 c = 0.0255 p = 5/17 d =0.003 or 0.008 1 − y = 0.535 a = 34/41 c = 0.0342 p = 5/17 d = 0.003 or0.008 1 − y = 0.535 a = 34/41 c = 0.0443 p = 5/17 d = 0.003 or 0.008

Such mixtures are preferably adjusted to the morphotropic phase boundary(MPB) in relation to the Zr to Ti ratio, and an excess of PbO as asintering aid is added if needed.

After dry or wet-chemical homogenization, the mixtures are typicallycalcined at 900-1000° C. The sintering activity can be adjusted to thedesired sintering temperature, e.g., in the range of 900-1200° C., withthe aid of fine grinding.

Using auxiliary agents such as dispersants and possibly other additives,the obtained powdered material is converted into a powder suspensionwith typically ca. 50-80% solids content. It can then be converted intopressable granular material by spray drying, for example, or can beprocessed directly into green ceramic films. To adjust the propertiesnecessary for further processing, typically 2-15% binders as well asfurther additives if needed can be added to the powder suspensions.

Disc-shaped pellets of powdered granular material are produced asspecimen bodies, while rectangular multilayer plates, referred to belowas MLPs are prepared by stacking and laminating green films. Binder isremoved from the sample bodies by the usual methods and processes.Piezoelectric multilayer actuators, which can contain up to severalhundred internal electrodes, also serve as sample bodies. In the case ofCu or other non-noble metals, attention must be paid to precisemonitoring and control of the furnace atmosphere during thermalprocessing in order to prevent an oxidation of the internal electrodesor a reduction of the ceramic.

The above-described piezoelectric materials allow a high sinteringcompression into ceramics with a textural structure that is veryadvantageous for the piezoelectric and electromechanical properties.After the specimen bodies have been provided with contacts, bysputtering for example, the dielectric and especially the piezoelectricproperties are measured. For piezoelectric multilayer actuators, thecontacts are advantageously provided by application and baking ofsuitable metal pastes. The piezoelectric materials with a Curietemperature in the range of ca. T_(C)≈250-380° C. are typicallypolarized at ca. 2 kV/mm.

Some of the measurement values and properties obtained with differentsample bodies of this type are compiled for the sake of example inTables 3-7.

In addition to the dielectric constant ∈, the expansion S according tothe relationship S₃=d₃₃×E₃, which holds for the piezoelectric effectunder the action of the electric field intensity E, was measured toobtain the piezoelectric constant d₃, where the index “3” describes thedirection of the axis established by the polarization as well as theapplied field intensity. The measured values for the dielectric loss arealso indicated. The loss is the ratio of electrical loss energy to thetotal electrical energy, and is derived from the surface area enclosedby the measured hysteresis curve.

TABLE 3 Small-signal and large-signal measurement values for disk MLPspecimens (diameter: 13 mm, height: 1 mm) and for multilayer actuators(350 Ag/Pd internal electrodes, thickness of the dielectric layers: 80μm, actuator surface area: 3.5 × 3.5 mm²) with piezoelectric material ofthe invention according to the formula:[Pb(Zr_(1−y)Ti_(y))O₃]_(0.973)[Sr₄(Sr_(4/3)Nb_(8/3))O₁₂]_(0.00213)[Sr(Zr_(1−y)Ti_(y))O₃]_(0.017)[PbV_(Pb)(Nb₂O₆)]_(0.003)(PbO)_(0.029)Field strength 1 − y Specimen [V/mm] ε d₃₃ [pm/V] Loss 0.52 MLP 20002588 634 0.455 0.525 MLP 2000 2672 658 0.445 0.53 MLP 2000 2687 6770.446 0.535 MLP 2000 1851 599 0.431 0.54 MLP 2000 2206 650 0.451 0.52MLP 1 1598 0.154 0.525 MLP 1 1670 0.0150 0.53 MLP 1 1419 0.0193 0.535MLP 1 1070 0.0206 0.54 MLP 1 1341 0.0184 0.52 Actuator 2000 3379 7010.408 0.52 Actuator 1 1669 0.0222

TABLE 4 Small-signal and large-signal measurement values for disc-shapedMLP specimens (diameter: 13 mm, height 1 mm) with piezoelectric materialaccording to the formula:[Pb(Zr_(1−y)Ti_(y))O₃]_(0.974)[Sr₄(Sr_(4/3)Nb_(8/3))O₁₂]_(0.00183)[Sr(Zr_(1−y)Ti_(y))O₃]_(0.0146)[PbV_(Pb)(NbO₃)]_(0.0097)(PbO)_(0.01)Field strength 1 − y Specimen [V/mm] ε d₃₃ [pm/V] Loss 0.53 MLP 20002724 659 0.476 0.53 MLP 1 2881 722 0.469

TABLE 5 Small-signal and large-signal measurement values for disc-shapedMLP specimens (diameter: 13 mm, height 1 mm) with piezoelectric materialaccording to the formula:[Pb(Zr_(1−y)Ti_(y))O₃]_(0.973)[Sr₄(Sr_(4/3)Nb_(8/3))O₁₂]_(0.0020)[Sr(Zr_(1−y)Ti_(y))O₃]_(0.0161)[PbV_(Pb)(NbO₃)]_(0.0117)(PbO)_(0.0078)Field strength 1 − y Specimen [V/mm] ε d₃₃ [pm/V] Loss 0.53 MLP 20002667 631 0.440 0.53 MLP 1 1683 0.0165

TABLE 6 Small-signal and large-signal measurement values for disc-shapedMLP specimens (diameter: 13 mm, height 1 mm) with piezoelectric materialaccording to the formula:[Pb(Zr_(1−y)Ti_(y))O₃]_(0.973)[Sr₄(Sr_(4/3)Nb_(8/3))O₁₂]_(0.0020)[Sr(Zr_(1−y)Ti_(y))O₃]_(0.0161)[PbV_(Pb)(NbO₃)]_(0.0093)(PbO)_(0.010)Field strength 1 − y Specimen [V/mm] ε d₃₃ [pm/V] Loss 0.535 MLP 20002870 674 0.497 0.535 MLP 1 1698 0.0167

TABLE 7 Small-signal and large-signal measurement values for disc-shapedMLP specimens (diameter: 13 mm, height 1 mm) with piezoelectric materialaccording to the formula:[Pb(Zr_(1−y)Ti_(y))O₃]_(0.973)[Sr₄(Sr_(4/3)Nb_(8/3))O₁₂]_(0.0020)[Sr(Zr_(1−y)Ti_(y))O₃]_(0.0161)[PbV_(Pb)(NbO₃)]_(0.0093)(PbO)_(0.010)Field strength 1 − y Specimen [V/mm] ε d₃₃ [pm/V] Loss 0.535 MLP 20002881 722 0.469 0.535 MLP 1 1727 0.0181

TABLE 8 Small-signal and large-signal measurement values for disc-shapedMLP specimens (diameter: 13 mm, height 1 mm) with piezoelectric materialaccording to the formula:[Pb(Zr_(1−y)Ti_(y))O₃]_(0.973)[Ba₄(Ca_(4/3)Nb_(8/3))O₁₂]_(0.00213)[Ba(Zr_(1−y)Ti_(y))O₃]_(0.0115)[Ca((Zr_(1−y)Ti_(y))O₃]_(0.0055)[Pb_(0.5)V_(Pb; 0.5)(NbO₃)]_(0.006)(PbO)_(0.02) Field strength 1 − y Specimen [V/mm] ε d₃₃[pm/V] Loss 0.535 MLP 2000 2609 610 0.510 0.535 MLP 1 1228 0.0201

By the appropriate selection of the ions for M₁ and M₂ and of parametersa, p and c, values for the dielectric constants and the piezoelectricconstant d₃₃ can be achieved which could previously only be achieved bythe addition of another component. For example, KNbO₃ or complexes thatcontain additional (heavy) metals such as Fe were contained asadditional components.

The materials used for the measurements of Tables 3-8, on the otherhand, preferably consist exclusively of the components P, D PbO andtheir reaction products. In these cases it was possible to forgo theaddition of another component Z entirely (d=0).

1. A piezoelectric material comprising: a material with the molecularformula P_(1−c−d)D_(c)Z_(d), wherein 0<c≦0.15 and 0≦d≦0.5, wherein Prepresents the composition Pb(Zr_(1−y)Ti_(y))O₃, where 0.50≦1−y≦0.60,wherein Z represents an additional component of the perovskite type ofstructure, wherein D represents a material according to the generalformula [(M₁O)_(1−p)(M₂O)_(p)]_(a)[Nb₂O₅]_(1−a), wherein M₁ representsBa_(1−t)Sr_(t) with 0≦t≦1, M₂ represents strontium, ⅔<a<1 and 0<p<1, andwherein the material D contains a cryolite type of structure.
 2. Thepiezoelectric material according to claim 1, wherein 0<c≦0.025.
 3. Thepiezoelectric material according to claim 1, wherein 0.0255<c<0.0443. 4.The piezoelectric material according to claim 1, wherein the materialcontains a mixed crystal comprising the component P with the structureof the perovskite type ABO₃ as the host lattice and the component D,wherein at least a part of the M₂ cations occupy the formal B-sites of aPZT perovskite host lattice of the material.
 5. The piezoelectricmaterial according to claim 1, wherein 6/7<a<1.
 6. The piezoelectricmaterial according to claim 1, wherein ⅔<a<⅘.
 7. The piezoelectricmaterial according to claim 1, wherein ⅘≦a≦ 6/7 and ¼≦p≦⅓, wherein thecomponent D has the general formula(M₁)₄[(M₂)_(2−2x/3)Nb_(2+2x/3)]O₁₁+_(x)V_(0;1−x) where 0≦x≦1, V_(O)represents oxygen vacancies, and a= 22/35+24p/35 and a= 6/7−2x/35, andwherein the component D with cryolite structure forms a solid solutionwith a PZT host lattice of the material.
 8. The piezoelectric materialaccording to claim 1, wherein the material additionally contains up to 5mol % PbO.
 9. The piezoelectric material according to claim 1, wherein acryolite compound according to the formula (M₁)₄[(M₂)₂Nb₂]O₁₁V_(O;1)forms a solid solution with a PZT host lattice of the material.
 10. Thepiezoelectric material according to claim 1, wherein the cryolitecompound is a constituent of component D and the excess of MO ofcomponent D is reacted at least in part with component P to formM(Zr_(1−y)Ti_(y))O₃ and PbO, wherein M represents M₁ or M₂.
 11. Thepiezoelectric material according to claim 1, wherein a cryolite compoundaccording to the formula (M₁)₄[(M₂)_(4/3)Nb_(8/3)]O₁₂ forms a solidsolution with a PZT host lattice of the material.
 12. The piezoelectricmaterial according to claim 1, wherein the cryolite compound is aconstituent of component D, and the excess of Nb₂O₅ of component D isreacted at least in part with additionally present PbO into leadniobate.
 13. The piezoelectric material according to claim 1, whereinthe material contains M(Zr_(1−y)Ti_(y))O₃ as a product of a reaction ofcomponent D with the PZT host lattice, wherein M represents M₁ or M₂.14. The piezoelectric material according to claim 1, wherein(M₁)₄[(M₂)_(4/3)Nb_(8/3)]O₁₂ is converted with the PZT host lattice atleast in part into lead niobate.
 15. The piezoelectric materialaccording to claim 1, wherein (M₁)₄[(M₂)_(5/3)Nb_(7/3)]O_(11.5)V_(O;0.5)is converted with the PZT host lattice at least in part into(M₁)₄[(M₂)_(4/3)Nb_(8/3)]O₁₂.
 16. The piezoelectric material accordingto claim 1, wherein (M₁)₄[(M₂)₂Nb₂]O₁₁V_(O;1) is converted with the PZThost lattice at least in part into(M₁)₄[(M₂)_(5/3)Nb_(7/3)]O_(11.5)V_(O;0.5).
 17. The piezoelectricmaterial according to claim 1, wherein, for component D: M₁=M₂=Sr, fromwhich a cryolite compound according to the formulaSr₄(Sr_(2−2x/3)Nb_(2+2x/3))O_(11+x)V_(O;1−x) results, wherein: 0≦x≦1,wherein a part of the Sr cations occupy the formal B-sites of theperovskite host lattice of component P.
 18. The piezoelectric materialaccording to claim 1, wherein the material contains Sr(Zr_(1−y)Ti_(y))O₃as a product of a reaction of component P with component D.
 19. Thepiezoelectric material according to claim 1, with the compositionP_(1−c−d)D_(c)Z_(d)[PbO]_(m). wherein D represents a cryolite compoundaccording to the formula [(SrO)_(a)(Nb₂O₅)_(1−a)] with a= 29/35, whichcan be expressed by the equivalent cryolite notationSr₄(Sr_(5/3)Nb_(7/3))O_(11.5)V_(0;0.5), wherein: 0<c≦0.15 and 0≦m≦0.05and d=0.
 20. The piezoelectric material according to claim 19, with thecomposition according to the formula:[Pb(Zr_(0.53)Ti_(0.47))O₃]_(0.973)[Sr₄(Sr_(4/3)Nb_(8/3))O₁₂]_(0.00213)[Sr(Zr_(0.53)Ti_(0.47))O₃]_(0.0017)[PbV_(Pb)(Nb₂O₆)]_(0.003)(PbO)_(0.029).21. The piezoelectric material according to claim 20, wherein about 10%of the strontium cations occupy formal B-sites of a PZT host lattice ofthe material.
 22. The piezoelectric material according to claim 1, withthe compositionP_(1−c−d)D_(c)Z_(d)[PbO]_(m), wherein D represents a cryolite compoundwith the formula:[(BaO)_(1−p)(CaO)_(p)]_(a)(Nb₂O₅)_(1−a)] with a= 29/35 and p= 7/24,which can be expressed by the equivalent cryolite notation,Ba₄(Ca_(5/3)Nb_(7/3))O_(11.5)V_(O;0.5), wherein: 0<c≦0.15 and 0≦m≦0.05and d=0.
 23. The piezoelectric material according to claim 22, with thecomposition according to the formula[Pb(Zr_(0.53)Ti_(0.47))O₃]_(0.973)[Ba₄(Ca_(4/3)Nb_(8/3))O₁₂]_(0.00213)[Ba(Zr_(0.53)Ti_(0.47))O₃]_(0.0115)[Ca(Zr_(0.53)Ti_(0.47))O₃]_(0.0055)[PbV_(Pb)(Nb₂O₆)]_(0.003)(PbO)_(0.029).
 24. The piezoelectric materialaccording to claim 23, wherein about 34% of the calcium cations occupyformal B-sites of the PZT host lattice.
 25. The piezoelectric materialaccording to claim 1, which forms a mixed-crystal phase that contains anadditional component Z.
 26. The piezoelectric material according toclaim 25, wherein the additional component comprises a compoundaccording to the formula [Pb(Fe^(III) _(2/3)W^(VI) _(1/3))O₃].
 27. Thepiezoelectric material according to claim 25, wherein the additionalcomponent comprises a compound according to the formula [Pb(M^(II)_(1/3)M^(V) _(2/3))O₃], wherein M^(II) represents Mg, Zn, Co, Ni, Mn orCu, and M^(V) represents Nb, Ta or Sb.
 28. The piezoelectric materialaccording to claim 25, wherein the additional component comprises acompound according to the formula [Pb(M^(III) _(1/2)M^(V) _(1/2))O₃],wherein M^(III) represents Fe, Mn, Cr or Ga and M^(V) represents Mb, Taor Sb.
 29. The piezoelectric material according to claim 25, wherein theadditional component comprises a compound according to the formula[Pb(M^(III) _(2/3)M^(VI) _(1/3))O₃], wherein M^(III) represents Mn, Cr,Ga and M^(VI) represents W.
 30. The piezoelectric material according toclaim 25, wherein the additional component comprises a compoundaccording to the formula [Pb(Li^(I) _(1/4)M^(V) _(3/4))O₃], whereinM^(V) represents Nb, Ta or Sb.
 31. The piezoelectric material accordingto claim 1, wherein the material is free of [Pb(Fe^(III) _(2/3)W^(VI)_(1/3))O₃].
 32. The piezoelectric material according to claim 1, whereinthe material is free of [Pb(Fe^(III) _(1/2)Nb_(1/2))O₃].
 33. Thepiezoelectric material according to claim 1, wherein the material isfree of KNbO₃.
 34. The piezoelectric material according to claim 1,wherein the material is free of Sr(K_(1/4)Nb_(3/4))O₃.
 35. Thepiezoelectric material according to claim 1, wherein about 10% of the Mcations occupy formal B-sites of a PZT host lattice of the material,wherein M represents M₁ and/or M₂.
 36. The piezoelectric materialaccording to claim 1, wherein for 6/7<a<1, the excess of MO of componentD is reacted at least in part with component P to formM(Zr_(1−y)Ti_(y))O₃ and PbO, wherein M represents M₁ or M₂.
 37. Thepiezoelectric material according to claim 1, wherein for ⅔<a<⅘, theexcess of Nb₂O₅ of component D is reacted at least in part withadditionally present PbO into lead niobate.
 38. The piezoelectricmaterial according to claim 1, wherein d=0.
 39. A piezoelectricmultilayer actuator comprising: at least one dielectric layer; and atleast two electrodes, wherein at least one dielectric layer contains apiezoelectric material according to claim
 1. 40. A method formanufacturing a piezoelectric component containing a material accordingto claim 1, wherein a concentration of the oxygen vacancies is increasedduring sintering and again lowered during cooling of the material.
 41. Amethod of manufacturing a piezoelectric multilayer actuator, the methodcomprising: forming a dielectric layer containing a piezoelectricmaterial according to claim 1; and forming at least two electrodesadjacent the dielectric layer.